The good answer is that `Boolean(x)` is the same as `‼x` (which is a good thing) - and the string "false" is truthy, since the only falsy string value is the empty string.
On Tue, Mar 21, 2017 at 1:08 PM, Dmitry Soshnikov < [email protected]> wrote: > On Tue, Mar 21, 2017 at 11:49 AM, Michael J. Ryan <[email protected]> > wrote: > >> I slightly disagree... mainly in that as it stands, we have a fairly >> loose type coercion system that allows almost anything to be coerced into a >> boolean... in this case "parse" at least in my mind means that it should >> cover the most common use cases. I understand that Boolean("false") >> doesn't currently work this way, and why Date.parse doesn't give a date >> instance is a bit beyond me. >> >> With my suggested polyfill your use case would work as expected... >> However, JS interacts with more than just serialized results from JS. It >> interacts with input from multiple systems, sources, users and good/bad the >> content of users. The type coercion as it exists for boolean is in order >> to provide for simplistic validation... why an empty string coerces false, >> for example. Much like we have defined "falsey" values in JS, I think that >> Boolean.parse should have common truthy values/strings that can predictably >> be converted as a true, where all else is false. >> >> If all it does is: >> >> input => String(input).toLowerCase() === 'true'; >> >> what is the point of extending Boolean? >> >> > Yeah, all good points, but they open a door for more questions mentioned > above (so many different formats, "yes", "1", "on", etc, and "why one, but > not another?", and "why not i18n?"). > > So to reduce this, having a good MVP would be good. Then, if there is a > need, it can be extended by adding. > > The actual practical use-case I want to solve is: > > - Not to use "raw building material" (aka "syntactic garbage") to solve > the issue. With this I mean using non-semantic techniques to achieve the > goal, like RegExp testings, JSON.parsing, etc. This is also a building > material: "String(input).toLowerCase() === 'true';", and users want nice > semantic library. > > - To solve `Boolean('false')` issue. This is an actual use-case I had, > when was asked why Boolean type coercion treats "false" as true, and there > is no good answer other than -- "it's specified so". So to keep backward > compats we need Boolean.parse(...) for this. > > So the only question it needs to address whether we accept truthy/false > values, or only strings. > > Dmitry > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
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